An employee clicked on a bogus link in an email that appeared to refer to administrative matters and loaded malware onto the computer, which allowed the attackers to penetrate the State Department’s network spanning thousands of systems across the US and its outposts.

In the clip above, President Obama’s deputy national security adviser Ben Rhodes says the White House uses a separate system for classified information. That’s hardly comforting, given how deep the hackers were able to get with an official looking email message.